Polyurethanes are produced by the reaction of polyisocyanates and polyols. The first large scale commercial production of polyurethanes arose using polyester polyols from the ester condensation reaction of diols or polyols and dicarboxylic acids to make flexible foams. The polyester polyols were supplanted by polyether polyols because of lower cost and ability to make a wide range of polyols. Polyethers are made by polymerizing epoxides (oxiranes) derived from petroleum feedstocks with active hydrogen starting compounds (polyols and polyamines).
Rigid polyurethane foams have been made with castor oil or castor oil byproducts. Castor oil has been used in rigid foams because of its low molecular weight (short chain length) and high functionality (trihydroxyl).
Attempts have been made to make polyols from vegetable or renewable feedstocks such as those disclosed by Peerman et al., U.S. Pat. Nos. 4,423,162; 4,496,487 and 4,543,369. Peerman et al. describe a method reacting a hydroxyester monomer with a polyol or polyamine. However, Peerman et al., specifically describe problems of gelling, which can be avoided by limiting the extent of conversion or by using quantities of reactants far from the amounts required stoichiometrically. Consequently, Peerman et al., only describe elastomers (crosslinked rigid polyurethanes) from their resultant polyols. In addition, the presence of secondary hydroxyls were described as causing sweating, wherein the product appears to be wet and not fully cured, thus limiting the use of low cost renewable initiators such as glycerol.
Accordingly, it would be desirable to provide both a formation method and a vegetable based polyol that solves one or more of the problems of the prior art, such as one of those described above. In particular it would be desirable to provide a vegetable oil based (VOB) polyol that can be used to make flexible polyurethane foams in the absence of any other polyols.